Which of the following represents the correct sequence for the collection of plant specimens?

Which of the following are true about the taxonomical aid 'key'?
$(a)$ Keys are based on the similarities and dissimilarities.
$(b)$ Key is analytical in nature.
$(c)$ Keys are based on the contrasting characters in pair called couplet.
$(d)$ Same key can be used for all taxonomic categories.
$(e)$ Each statement in the key is called Lead.
Choose the most appropriate answer from the options given below:

Who works under the supervision of the $CZA$?

What are taxonomical aids?

Ecological,economic,and ethnobotanical information is obtained from .........

Assertion $(S)$: Rare genes can be preserved in botanical gardens.
Reason $(R)$: Gene banks are developed in botanical gardens.
$(A)$ Both $S$ and $R$ are true,and $R$ is the correct explanation of $S$.
$(B)$ Both $S$ and $R$ are true,but $R$ is not the correct explanation of $S$.
$(C)$ $S$ is true and $R$ is false.
$(D)$ $S$ is false and $R$ is true.